Arista EOS: Incorrect WAN path selection via crafted BGP-LS packet
Summary
Arista EOS devices configured for Pathfinder WAN path selection with BGP-LS for Dynamic Path Selection (DPS) can be affected. An attacker with an authenticated BGP-LS session to the device can send a specially crafted BGP packet. This can cause incorrect WAN path selection and disrupt traffic forwarding. Confidentiality is not affected according to the CVSS vector.
Affected
- Arista EOS 4.36.0F to 4.36.2F
- Arista EOS 4.35.0F to 4.35.6M
- Arista EOS 4.34.0F to 4.34.8M
- Arista EOS 4.33.0F to 4.33.10M
- Arista EOS 4.32.0F to before 4.33.0F
- Arista EOS 1.0.0 to before 4.32.0F
- Only with BGP-LS configured for DPS (Pathfinder role)
Fixed in
Unknown. Check the Arista security advisory 0212.
Workaround
Unknown. No vendor mitigation was found in the available sources. General measures: limit who can establish BGP-LS sessions and verify BGP peer configuration and authentication.
Exploitation
- No evidence of exploitation in the wild known at time of writing.
- No public proof of concept found.
- CISA KEV: not listed.
Our recommendation
- Check whether Arista Pathfinder/DPS with BGP-LS is in use. If not, no action is needed for this CVE.
- If it is in use, check the affected versions against your device inventory.
- Restrict BGP-LS peering to known peers and verify authentication settings.
- Monitor for unexpected WAN path changes.
- Plan the upgrade once the vendor advisory confirms the fixed release.
Public exploits
PoC-in-GitHub, Metasploit and Exploit-DB list nothing for this CVE.
Research sources
- Arista Security Advisory 0212 www.arista.com
- CVE Record CVE-2026-120979 www.cve.org
- Strix CVE-2026-120979 www.strix.ai
- ThreatInt CVE-2026-120979 cve.threatint.com
Researched and written up in English and German by an AI (Claude by Anthropic) based on NVD, CISA, EPSS and the sources listed. The vendor information is authoritative. Researched on 11 Nov 2026, 14:17.
Original description (NVD)
This vulnerability affects customers using Arista Pathfinder for WAN path selection with Border Gateway Protocol-Link State (BGP-LS) configured for Dynamic Path Selection (DPS). On affected platforms running Arista EOS with BGP-LS configured for DPS, an attacker who has established an authenticated BGP-LS session with the device can send a specially crafted BGP packet to cause incorrect WAN path selection and disrupt traffic forwarding.
Sources
The tracker combines official, freely usable data sources – updated continuously:
- NVD (NIST) – CVEs, rating (CVSS), affected products
- CISA KEV – vulnerabilities confirmed by CISA as actively exploited
- CISA Vulnrichment – CISA assessment (SSVC) in the official CVE record
- FIRST EPSS – probability of exploitation
- Microsoft MSRC – Patch Tuesday: vulnerabilities, severity, updates
- PoC-in-GitHub – public proof-of-concept repositories
- Metasploit (Rapid7) – modules of the Metasploit Framework
- Exploit-DB (OffSec) – archive of public exploits (links only)
- Patch days: official vendor pages (linked per vendor) (Vendor patch days)
This product uses data from the NVD API but is not endorsed or certified by the NVD. EPSS data © FIRST.org.
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